Question: I tried to connect my device to your DS100B over RS485 (2m cable). I have strange results:
When connecting both devices to a single 12V adapter, communication over 485 does NOT work.
When connecting each device to its own adapter, communication over 485 starts working.
When connecting both devices to a single adapter, but using RS232 instead of RS485 it also works.
How come? Any suggestions?
Answer: This happens beacuse when connecting two DSes to one PSU, you connect them to the same ground (the minus signal of the PSU).
RS485 does not work when both ends of the line are connected to the same ground. It requires different ground connections on either end of the line.
So, this is a protocol issue – not device-specific. For a 485 connection to work, you must use two different PSUs.
